{
 "cells": [
  {
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   "metadata": {},
   "source": [
    "# Matrix Factorization (MF) Example\n",
    "Demonstrates matrix factorization with MXNet on the [MovieLens 100k](http://grouplens.org/datasets/movielens/100k/) dataset. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "import mxnet as mx\n",
    "from movielens_data import get_data_iter, max_id\n",
    "from matrix_fact import train"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "train_test_data = get_data_iter(batch_size=50)\n",
    "max_user, max_item = max_id('./ml-100k/u.data')\n",
    "(max_user, max_item)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Linear MF"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "def plain_net(k):\n",
    "    # input\n",
    "    user = mx.symbol.Variable('user')\n",
    "    item = mx.symbol.Variable('item')\n",
    "    score = mx.symbol.Variable('score')\n",
    "    # user feature lookup\n",
    "    user = mx.symbol.Embedding(data = user, input_dim = max_user, output_dim = k) \n",
    "    # item feature lookup\n",
    "    item = mx.symbol.Embedding(data = item, input_dim = max_item, output_dim = k)\n",
    "    # predict by the inner product, which is elementwise product and then sum\n",
    "    pred = user * item\n",
    "    pred = mx.symbol.sum_axis(data = pred, axis = 1)\n",
    "    pred = mx.symbol.Flatten(data = pred)\n",
    "    # loss layer\n",
    "    pred = mx.symbol.LinearRegressionOutput(data = pred, label = score)\n",
    "    return pred\n",
    "\n",
    "net1 = plain_net(64)\n",
    "mx.viz.plot_network(net1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "scrolled": false
   },
   "outputs": [],
   "source": [
    "results1 = train(net1, train_test_data, num_epoch=15, learning_rate=0.02)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Neural Network (non-linear) MF"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "scrolled": false
   },
   "outputs": [],
   "source": [
    "def get_one_layer_mlp(hidden, k):\n",
    "    # input\n",
    "    user = mx.symbol.Variable('user')\n",
    "    item = mx.symbol.Variable('item')\n",
    "    score = mx.symbol.Variable('score')\n",
    "    # user latent features\n",
    "    user = mx.symbol.Embedding(data = user, input_dim = max_user, output_dim = k)\n",
    "    user = mx.symbol.Activation(data = user, act_type='relu')\n",
    "    user = mx.symbol.FullyConnected(data = user, num_hidden = hidden)\n",
    "    # item latent features\n",
    "    item = mx.symbol.Embedding(data = item, input_dim = max_item, output_dim = k)\n",
    "    item = mx.symbol.Activation(data = item, act_type='relu')\n",
    "    item = mx.symbol.FullyConnected(data = item, num_hidden = hidden)\n",
    "    # predict by the inner product\n",
    "    pred = user * item\n",
    "    pred = mx.symbol.sum_axis(data = pred, axis = 1)\n",
    "    pred = mx.symbol.Flatten(data = pred)\n",
    "    # loss layer\n",
    "    pred = mx.symbol.LinearRegressionOutput(data = pred, label = score)\n",
    "    return pred\n",
    "\n",
    "net2 = get_one_layer_mlp(64, 64)\n",
    "mx.viz.plot_network(net2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "scrolled": false
   },
   "outputs": [],
   "source": [
    "results2 = train(net2, train_test_data, num_epoch=15, learning_rate=0.02)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Visualizing results\n",
    "Now let's draw a single chart that compares the learning curves of the three different models.\n",
    "We'll use the bokeh library since it gives nice interactive charting."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "import bokeh\n",
    "import bokeh.io\n",
    "import bokeh.plotting\n",
    "bokeh.io.output_notebook()\n",
    "import pandas as pd\n",
    "\n",
    "def viz_lines(fig, results, legend, color):\n",
    "    df = pd.DataFrame(results._data['eval'])\n",
    "    fig.line(df.elapsed,df.RMSE, color=color, legend=legend, line_width=2)\n",
    "    df = pd.DataFrame(results._data['train'])\n",
    "    fig.line(df.elapsed,df.RMSE, color=color, line_dash='dotted', alpha=0.1)\n",
    "\n",
    "fig = bokeh.plotting.Figure(x_axis_type='datetime', x_axis_label='Training time', y_axis_label='RMSE')\n",
    "viz_lines(fig, results1, \"Linear MF\", \"orange\")\n",
    "viz_lines(fig, results2, \"MLP\", \"blue\")\n",
    "\n",
    "bokeh.io.show(fig)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "collapsed": true
   },
   "source": [
    "## Acknowledgement\n",
    "\n",
    "This tutorial is based on examples from [xlvector/github](https://github.com/xlvector/)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "# What if we let the linear model train for as long?\n",
    "results1 = train(net1, train_test_data, num_epoch=30, learning_rate=0.02)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Next steps\n",
    "See [this notebook](demo1-MF2-fancy.ipynb) to try using fancier network structures and optimizers on this same problem."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": []
  }
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